1. Field of the Invention
The present invention relates generally to diethynylated aromatic compounds. More particularly, the present invention relates to diphenylhexafluoropropane compounds having an ethynylphenoxy or ethynylthiophenoxy group attached to the phenyl rings of the diphenylhexafluoropropane.
2. Description of the Background Art
Diethynylated aromatic compounds are important intermediates in the synthesis of thermally stable resins for use in high-temperature structural composites, and high-char yielding structure matrices, such as carbon-carbon composites. These materials are used in the fabrication of reentry missile nose cones, leading edges, rocket nozzles, and other structural applications requiring high structural strength and high thermal stability.
The processing and fabrication of these high temperature resins is generally rather difficult. When using the diethynylated aromatic compounds by themselves or as diluents in various high temperature resins and composite products, it is important that the compound be in a fluid state over a relatively large workable temperature range in order to facilitate processing. This workable or fluid temperature range is generally referred to as the "processing window" for the given diethynylated aromatic compound. The lower limit of the processing window is the temperature at which the compound melts to a liquid state, while the upper limit is the temperature at which the compound gels and solidifies. If possible, it is desirable to use compounds which have processing windows encompassing ambient temperatures in order to simplify resin fabrication and make the process commercially practical.
There are presently only two known diethynylated aromatic compounds which are viscous liquids at ambient temperatures. One is an acetylene-terminated sulfone (ATS) and the other is 2,2-bis(4-ethynylphenyl) hexafluoropropane (EPHFP). EPHFP and related compounds are disclosed in U.S. Pat. No. 4,374,291 which issued Feb. 15, 1983, to the same assignee as the present invention. It would be desirable to provide additional diethynylated aromatic compounds which have processing windows in the same range as the above discussed known compounds and which also provide additional properties and characteristics not found in either of the two known compounds.